All the more reason for property owners to occasionally assert their rights.
Once a year, Stanford University, which is adjacent to Palo Alto, California goes around and blocks off the various accesses to the university. The the casual observer the relatively large campus has a number of public roads running through it. In reality the campus is all private land. So to maintain ownership they assert their rights by closing down each of the roads for an hour or two each year. Typically done one at a time, 2AM Sunday morning, but it does meet the legal requirements of what is needed to maintain full ownership.